The present invention relates to an oil-pressure warning apparatus for alarming when the circulation pressure of engine oil drops.
Conventionally, these types of apparatuses are of the construction in which an oil-pressure switch 1 is connected in series with a vehicle-carried battery 4 via a warning lamp 2 as warning means and an ignition switch 3. When the circulation pressure of engine oil has dropped below a predetermined level, the oil-pressure switch 1 is turned on to cause the warning lamp 2 to light up. Thus, if the engine is normally operating and the circulation pressure of engine oil is higher than a predetermined level, the warning lamp 2 is. If the oil pressure drops due to, for example, a decrease in the amount of oil, the oil pressure switch 1 is turned on to cause the warning lamp 2 to light up, thus warning the user.
Practically, the circulation pressure of engine oil of an actual automobile varies in accordance with the operating conditions of the engine. With the above-mentioned construction, if a change in circulation oil pressure occurs just below or above the predetermined level, the oil pressure switch 1 opens and closes in response to the variations of the pressure, causing the warning lamp 2 to flash intermittently, in which case the flashing may stop due to the fact that the circulation pressure becomes temporarily higher than the predetermined level, allowing the warning lamp 2 to light out. Thus, the conventional apparatus suffers from the drawbacks in that it is difficult for the users to identify whether the temporary flashing is really a warning of the decreased circulation pressure of engine oil.